Three years after winning the 1989 Booker prize for The Remains of the Day, Kazuo Ishiguro said, in an interview with Pico Iyer, that he felt he could “produce something pretty strange and weird now”. In 1995, he delivered on that promise with The Unconsoled, an enigmatic, mazy and Kafkaesque journey through a nameless European country, as unlike The Remains as anyone could have wished for. Since then, he has taken us (less strangely) to 1930s China (When We Were Orphans) and (more strangely) the imaginary British dystopia of Never Let Me Go, where children are raised as organ donors; but this novel might be his strangest yet.

We are in post-Arthurian, pre-Norman Britain; Saxons and Britons coexist in an uneasy but functioning truce, yet the land is wreathed in icy mists – the exhalation of a she-dragon, we learn, whose effect is to rob people of their memories. We follow an ageing couple, Axl and Beatrice, who live in a British settlement composed of tunnels dug into a hillside. They decide to journey to a village, a few days’ walk away, to visit their son; they can hardly remember him, but assume he will be waiting “impatiently” to see them.

We are in a weird world indeed, not just because it is populated by ogres, sprites, demons and dragons, but also because Ishiguro puts a fog over the narrative, littering it with elisions, false turns and feints that make us doubt what we have read. There will be a big setup for a battle, say – Ishiguro relishes the technical details of swordplay, or of how to construct a tower so that it will become a deadly trap for those seeking to storm it – and then the scene will happen offstage, as it were. We might even doubt whether it happened at all.

This is partly, I think, to subvert the very genre he has adopted. It’s a world laden with echoes from the ancient British myth-kitty, and the various raids on it by previous writers: Gawain is here, aged and in endless, fruitless pursuit of Querig, the mist-breathing dragon, bringing to mind TH White’s hapless King Pellinore and the Questing Beast. There are hints of Malory, Beowulf and Grendel, and, inevitably, Tolkien, whose example bequeaths a seriousness of purpose, or an impression of it. But it is as if Ishiguro is as keen to dodge the label of fantasy as he is to court it. When we are told, two‑thirds of the way through, that “most people” smell of “stale excrement”, I can’t have been alone in being reminded of the line in Monty Python and the Holy Grailwhere you can tell if someone is a king because “he hasn’t got shit all over him” – not that Ishiguro would have his characters say such a thing. The dialogue is uniformly archaic, leaden almost (“I wish it right enough, sir,” etc), as if a distinctive voice would itself be anachronistic.

At first I suspected allegory. When, early on, we enter a Saxon village whose inhabitants are moved to senseless rage, I wondered if the picture of a populace without memory, easily swayed to strong emotion, prey to beasts that may be imaginary, was a rebuke to modern life, and that he was actually writing about, say, the internet.

That may be too specific, but the book can be applied to our own times. It turns out that the collective amnesia of the dragon’s breath may have a more benign purpose than we first thought. The centre of the story is Axl and Beatrice’s love for each other; but when the dragon is slain, what will they remember? The bad times, as well as the good? And what will the Britons and Saxons recall from past battles? It all heads to a sad and desperate conclusion, and, in common with the best examples of the genre, connives to unravel its own world.